June 22, 2006 — ABC News has learned that federal agents, including the FBI, are launching a series of raids tonight targeting a suspected terror cell based in Miami.

According to sources familiar with the investigation, the group allegedly planned to bomb the FBI building in Miami and the Sears Tower in Chicago.

The group has been under surveillance for some time and was infilitrated by a government informant who allegedly led them to believe he was an Islamic radical. The suspects are described as African Americans and at least one man of Caribbean descent.

Sources say the arrests reflect the government's concern about so-called "homegrown terrorists." It's a threat FBI Director Robert Mueller discussed during a recent speech in New York.

Attorney General Alberto Gonzales and the FBI are expected to hold a press conference about the arrests Friday morning.